You want some word other than trail there, Tufguy. Fix the verb and change that word and you can have a good sentence.
That's OK.We need to breathe in fresh air where there is no sign of pollution.
You really don't need the "in". Breathing includes inhaling and exhaling. However, it's acceptable as it is.
I suggest that the intent is "no trace of pollution".
In what context would you use that sentence, tufguy?